An egg vendor calls on his first customer, and sells half of his eggs and half an egg.
To the second customer, he sells two-thirds of what was remaining and one-third of an egg.
To the third customer, he sells three-fourths of what was remaining and one-fourth of an egg.
To the fourth customer, he sells four-fifths of what was remaining and one-fifth of an egg

The vendor had precisely three eggs at the end of the fourth transaction.

The total number of eggs at the beginning was a whole number. No broken eggs were sold nor were any egg broken in between any two steps or after the last step.